Get 15 percent off all used books today only at Better World Books, a for-profit organization that collects and sells books online to benefit literacy initiatives in the U.S. and abroad. The sale is in celebration of International Literacy Day. Use code 4Literacy at checkout.

Used titles include The Pillars of the Earth by Ken Follet for $7, Harry Potter and the Half-Blood Prince for $4.50 and Green Eggs and Ham for $4. Check out their bargain bin, where 5 used books are $15.

Find popular books  by looking at Oprah’s book club, Amazon best sellers, and bargain best sellers. Perhaps you will find some early Christmas presents!

Better World Books conducts book drives on 1,800 college campuses and collects discards from more than 1,800 libraries. The company has raised $7 million for its non-profit literacy, library and college partners, donated over 1.3 million college textbooks and diverted more than 25 million pounds of books from landfills, according to a press release. Read more about Better World Books.